The proposed research is designed to further evaluate and answer critical questions regarding the concept of using the zona pellucida as a target antigen for immunocontraception. Part I involves the heteroimmunization of mice with varying dosages of isolated porcine zonae pellucidae and monitoring the resultant immunologic response in regard to antibody titer versus pig and mouse zonae, duration and characteristics of the response and any anti-fertility effect produced. Anti-zona pellucida activity will be assessed by standard tests such as observing the antibody produced precipitation layer on the zona, the indirect fluorescent antibody method and radioimmunoassay. Part II involves the biochemical purification of porcine zona antigen using chromatographic and electrophoretic techniques and the physiochemical characterization of the purified antigen. Antibodies produced against the purified antigen will be characterized regarding their contraceptive potency, tissue specificity and species cross-reactivity.